Add docs for general node upgrade

[iameskild]

Fixes | Closes | Resolves #1124

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Changes introduced in this PR:

• Add an FAQ on the possibility of an inplace upgrade to the general node instance type.

Types of changes

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features to not work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
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Testing

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Documentation

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• Yes, docstrings
• Yes, main documentation
• Yes, deprecation notices

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[iameskild]

If I have time this week, I will try to test node upgrades for these two providers as well.